<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script>
			String.prototype.equals=function(n){
				var f= this.indexOf(n);
				return f==0&&n.length==this.length;
			}
			//prototype
			var str="java";
			alert(str.equals("java"));
			alert(str.equals("Java"));
		</script>
	</head>
	<body>
	</body>
</html>
